Method for production of optical module and optical module

Abstract

An optoelectronic component is mounted at a precise position on a waveguide substrate so as to reduce loss in propagating light, and electrically connect electrodes on the waveguide substrate and the optoelectronic component. The waveguide substrate has an optical waveguide and a recessed portion for mounting the optoelectronic component, and electrodes are arranged on the recessed portion. A great number of globular elastic conductive particles are distributed on the bottom surface of the recessed portion. Thereafter, the optoelectronic component is placed in the recessed portion so as to press the globular elastic conductive particles, and alignment between the optical waveguide in the waveguide substrate and an optical waveguide in the optoelectronic component is adjusted. Then, the optoelectronic component is fixed to the waveguide substrate with an optical adhesive while the alignment is precisely adjusted.

1. A method for production of an optical module in which an optoelectronic component having at least one first electrode on a bottom surface of the optoelectronic component is mounted on a waveguide substrate having an optical waveguide, a recessed portion, and at least one second electrode formed on the recessed portion in correspondence with said at least one first electrode, said method comprising the steps of:
 (a) distributing globular elastic conductive particles on a bottom surface of the recessed portion of the waveguide substrate and at least one upper surface of the at least one second electrode; 
 (b) placing the optoelectronic component in the recessed portion of the waveguide substrate so that the at least one first electrode is respectively opposed to the at least one second electrode through at least a portion of the globular elastic conductive particles which is located on the at least one upper surface of the at least one second electrode; 
 (c) adjusting alignment between the optoelectronic component and the waveguide substrate by pressing the optoelectronic component toward the waveguide substrate so that the at least one first electrode is respectively electrically connected to the at least one second electrode through at least one portion of the globular elastic conductive particles; and 
 (d) fixing the optoelectronic component to the waveguide substrate so that the optoelectronic component is aligned with the waveguide substrate. 
 
   
   
     2. A method according to  claim 1 , wherein grooves each having a width greater than diameters of the globular elastic conductive particles are arranged in advance at both ends, in a direction in which light propagates through said optical waveguide, of the bottom surface of said recessed portion. 
   
   
     3. A method according to  claim 1 , wherein the number of said at least one first electrode is more than one, the number of said at least one second electrode is more than one, said globular elastic conductive particles each have a diameter smaller than each of a space between adjacent ones of said at least one first electrode and a space between adjacent ones of said at least one second electrode. 
   
   
     4. A method according to  claim 1 , wherein each of said globular elastic conductive particles is a globular elastic particle made of an organic material and coated with a conductive metal. 
   
   
     5. A method according to  claim 1 , wherein said optoelectronic component is fixed to said waveguide substrate with an optical adhesive. 
   
   
     6. A method according to  claim 1 , wherein said optoelectronic component is an optical deflection element which comprises an optical waveguide formed of a material exhibiting an electro-optic effect, on a conductive substrate, and one or more prismatic electrodes arranged opposite to the substrate across the conductive substrate; and the optical deflection element is fixed to the waveguide substrate so that the one or more prismatic electrodes face toward the bottom surface of the recessed portion, and the optical waveguide in the optical deflection element is aligned with the optical waveguide. 
   
   
     7. An optical module, comprising:
 an optoelectronic component having a first waveguide; 
 a waveguide substrate having a second waveguide, the waveguide substrate having a recessed portion for placing said optoelectronic component; 
 at least one first electrode arranged on a bottom surface of the recessed portion; 
 at least one second electrode arranged on a bottom surface of said optoelectronic component in correspondence with said at least one first electrode; and 
 globular elastic conductive particles distributed on the bottom surface of the recessed portion and an upper surface of the at least one first electrode; 
 wherein said optoelectronic component is fixed to the waveguide substrate in such a manner that the optoelectronic component presses the globular elastic conductive particles, and 
 wherein said first waveguide and said second waveguide are aligned. 
 
   
   
     8. A method for production of an optical module in which an optoelectronic component having at least one first electrode on a bottom surface of the optoelectronic component is mounted on a waveguide substrate having an optical waveguide and at least one second electrode which is respectively formed in correspondence with said at least one first electrode, said method comprising the steps of:
 (a) concentratedly depositing globular elastic conductive particles on and around the at least one second electrode; 
 (b) placing the optoelectronic component on the globular elastic conductive particles so that the at least one first electrode is respectively opposed to the at least one second electrode, and at least one portion of the globular elastic conductive particles is located between the at least one first electrode and the at least one second electrode; 
 (c) adjusting alignment between the optoelectronic component and the waveguide substrate by pressing the optoelectronic component toward the waveguide substrate so that the first and second electrodes are electrically connected through at least one portion of the globular elastic conductive particles; and 
 (d) fixing the optoelectronic component to the waveguide substrate so that the optoelectronic component is aligned with the waveguide substrate. 
 
   
   
     9. A method according to  claim 8 , wherein the number of said at least one second electrode is more than one, and said globular elastic conductive particles are concentratedly deposited on and around said at least one second electrode in step (a) by forming a protrusion between said at least one second electrode on the waveguide substrate, and distributing the globular elastic conductive particles on the waveguide substrate on which the protrusion is formed. 
   
   
     10. A method according to  claim 9 , wherein in step (a), a portion of the globular elastic conductive particles which remains on said protrusion is removed by using an element having an adhesive surface. 
   
   
     11. A method according to  claim 9 , wherein said protrusion has a height above an upper surface of the waveguide substrate, and the height is smaller than diameter of each of the globular elastic conductive particles, and greater than half of the diameter of each of the globular elastic conductive particles. 
   
   
     12. A method according to  claim 9 , wherein said protrusion is made of an insulating material. 
   
   
     13. A method according to  claim 8 , wherein in step (a), said globular elastic conductive particles are concentratedly deposited on and around the at least one second electrode by applying an adhesive to the at least one second electrode and at least one vicinity of the at least one second electrode, and distributing the globular elastic conductive particles on the waveguide substrate so that the globular elastic conductive particles adhere to the adhesive. 
   
   
     14. A method for production of an optical module in which an optoelectronic component having at least one first electrode on a bottom surface of the optoelectronic component is mounted on a waveguide substrate having an optical waveguide and at least one second electrode which is respectively formed in correspondence with said at least one first electrode, said method comprising the steps of:
 (a) forming a mask which protects the waveguide substrate except for said at least one second electrode and at least one vicinity of the at least one second electrode; 
 (b) applying a first adhesive containing globular elastic conductive particles to said waveguide substrate on which said mask is formed; 
 (c) removing the mask; 
 (d) applying a second adhesive to the waveguide substrate; 
 (e) placing the optoelectronic component on the waveguide substrate so that the at least one first electrode is respectively opposed to the at least one second electrode, and at least one portion of the globular elastic conductive particles is located between the first and second electrodes; 
 (f) adjusting alignment between the optoelectronic component and the waveguide substrate by pressing the optoelectronic component toward the waveguide substrate so that the first and second electrodes are electrically connected through at least one portion of the globular elastic conductive particles; and 
 (g) fixing the optoelectronic component to the waveguide substrate by curing the first and second adhesives so that the optoelectronic component is aligned with the waveguide substrate. 
 
   
   
     15. A method according to  claim 14 , wherein said first adhesive has a first viscosity which is equal to or greater than a second viscosity which said second adhesive has. 
   
   
     16. A method according to  claim 14 , further comprising, after step (c), a step of (c 1 ) partially curing said first adhesive, wherein said second adhesive is applied, in step (d), to the waveguide substrate on which the first adhesive is partially cured. 
   
   
     17. A method according to  claim 14 , wherein said first adhesive is made of a thermosetting resin, and said second adhesive is made of an ultraviolet-curing resin. 
   
   
     18. A method according to  claim 14 , wherein said first adhesive is made of an ultraviolet-curing resin, and said second adhesive is made of a thermosetting resin. 
   
   
     19. A method according to  claim 14 , wherein said first and second adhesives are each made of a thermosetting resin, said method further comprises, after step (c), a step of (c 1 ) partially curing said first adhesive by heating the first adhesive at a first temperature, said second adhesive is applied, in step (d), to the waveguide substrate on which the first adhesive is partially cured, and the first and second adhesives are cured in step (g) by heating the first and second adhesives at a second temperature which is higher than the first temperature. 
   
   
     20. An optical module comprising:
 a waveguide substrate which has at least one first electrode, and in which a first optical waveguide is formed; 
 an optoelectronic component which has at least one second electrode and a second optical waveguide; and 
 globular elastic conductive particles concentratedly deposited on and around the at least one first electrode of the waveguide substrate; 
 wherein the at least one first electrode is respectively electrically connected to the at least one second electrode through the globular elastic conductive particles, and 
 wherein said first optical waveguide and said second optical waveguide are aligned. 
 
   
   
     21. An optical module according to  claim 20 , wherein the number of said at least one second electrode is more than one, and a protrusion is formed between said at least one first electrode on the waveguide substrate. 
   
   
     22. An optical module according to  claim 20 , wherein gaps between said waveguide substrate and said optoelectronic component are filled with resins of more than one type each of which have a function of an adhesive. 
   
   
     23. An optical module according to  claim 22 , wherein portions, of the gaps between said waveguide substrate and said optoelectronic component, in which optical paths between the optoelectronic component and said optical waveguide exist are filled with a resin which has a function of an optical adhesive.